A modulated electron beam incident on a reverse-biased semiconductor p-n junction can be used to modulate the density of charge carriers and, therefore, the current flowing through the junction. The effect is similar to the modulation produced by a photon beam on a semiconductor; modulation of the photon beam produces, by means of the photoelectric effect, a modulation of the charge carrier density in the semiconductor. Electron beams with beam energies of approximately ten keV can be used to produce a substantial current gain, of the order of more than 10.sup.3 in semiconductor p-n junctions. This is the basis of the hybrid electron-beam semiconductor (EBS) technology.
Typically EBS structures consist of an electron-beam source, a high-frequency modulation arrangement for modulation of the electron beam and a p-n junction target all enclosed in a high-vacuum envelope. The modulation may be produced by a small potential applied to a grid which controls the e-beam current or a deflection system which moves the beam from one diode to another, when several diodes are arranged in a diode matrix array representing the target for the beam, and an output circuit connected to an external load of the EBS structure. Heretofore, the EBS device technology has been applied primarily with silicon p-n junctions as the appropriate targets in UHF and VHF amplifier configurations, a typical one being shown schematically in FIG. 1. Recent advances typified by the above reference to the related patent of Herman H. Wieder have expanded the field of EBS application to include heterojunction field effect transistors. Both the diodes and the field effect transistor modulation by EBS have been limited to the magnitudes of the output currents as well as the impressed frequency response.